Crispy French Fries

ABSTRACT

Crispy French fry-style food products are prepared by modification of the water content and the texture of the products&#39; surface layers prior to deep frying. The surface modifications include surface firming, enzyme treatments, starch infusion and/or ultrasound treatment.

TECHNICAL FIELD

The present application relates, in general, to culinary science and food preparation technology. In particular, the application relates to deep fried food products.

DESCRIPTION

Attention is being given to preparing crispy deep fried food products (e.g., chips, French fries. etc).

The deep fried food products (herein after “French fry-style food product of “French fries”) may be prepared, for example, from fresh potatoes that are peeled, sliced and cooked in kitchens. In the fast food industry, local stores or restaurants acquire frozen fresh, blanched or par-cooked food product that has been cut, pre-sliced, or otherwise formed in to a suitable shape (e.g. strips, cubes or slices). The local stores or restaurants defrost and “finish” deep-fry the par-cooked food product in edible oil before serving it as French fries.

Heat causes hydration and expansion of starch granules in the food product, which a consumer may experience as cooked texture and flavor. Rapid heating removes water from the outer layers of the deep fried product, which may give rise to the formation of a crisp but light and expanded material. Maillard browning reactions (see Whistler, R. I. and Daniel, J. R. 1985, Carbohydrates in “Food Chemistry” Second Edition, Marcel Dekker Inc. New York, Owen R. Fennema ed., pg. 96-105) between amino groups of amino acids and small amounts of sugars in the potato product give the golden color and a toasted flavor which are characteristic of freshly prepared French fries. Some conventional cooking recipes call for coating or pre-coating the food products with batter slurry or other coating material (e.g. a sugar solution) for flavor and to give a golden coloring. Further, batter slurry or other coating material may include ingredients that resist rehydration and prolong the crispiness of the finished food products, for example, when they are subject to conditions of high heat and humidity. Reducing the rehydration may inhibit the food product from becoming undesirably limp, soggy or tough and hold its crispiness quality for an extended period of time. Examples of rehydration-resistant coating materials include a hydrocolloid pre-coating applied prior to coating the food product with a batter; an aqueous slurry containing chemically modified, ungelatinized potato starch, chemically modified, ungelatinized corn starch, and rice flour; a coating of high amylose starch; a glaze coating of hydrolyzed starch; a batter mix containing a leavening agent, a blend of starch and high amylose starch, dextrin and a food gum; and a slurry of corn flour, corn starch and low solubility dextrin.

Specific EXAMPLES I-IV of “crispy” French fry-style food products and methods for making the same are presented herein. It will be understood that EXAMPLES I-IV are presented only for purposes of illustration and are not intended to limit the scope of the disclosure.

The cooking methods described herein may be exploited to prepare small quantities (e.g., individual food servings prepared in home kitchens) and/or large quantities (e.g., commercial food servings prepared in industrial kitchens or other commercial food processing industry).

The preparation of the French fry-style food products may be carried out in increments or stages. Pre-cooked or partially cooked intermediate items may be stored (e.g., frozen or unfrozen) for later cooking to completion. One or more of the cooking increments or stages may involve “sous-vide” cooking, which is a cooking technique that is intended to maintain the integrity of ingredients by heating them for an extended period at relatively low temperatures. In sous-vide cooking, the food products (e.g., potato cuts or strips) may be cooked for a time in airtight containers (e.g., airtight plastic bags) placed in hot water at or below its boiling point (100° C.).

The preparation of the French fry-style food products described herein involve modification of the water content and the texture of the products' surface layers prior to deep frying in order to obtain suitable crispiness in the finished products. Surface modifications may include surface firming using, for example, enzyme treatments and/or starch infusion. Additional or alternate surface modifications involve application of ultrasound. Surface modifications may also involve control of the water content of the surface layers by drying or desiccation prior to deep frying.

The following non-limiting EXAMPLES I-IV illustrates intermediate- and finish-cooked crispy French fry-style vegetable products, and the methods of preparing the same.

EXAMPLE I Pectinase-Steeped Crispy Fries

Pectinase-steeped crispy French fries were prepared.

Russet potatoes (500 g) were cut into batons about 1.5 cm thick and thoroughly rinsed in water to wash away native surface starch. The rinsed potatoes were treated with approximately 1/2% solution of a surface-firming enzyme (e.g. a pectic enzyme). The surface-firming enzyme solution was prepared by mixing 2 g of Pectinex Ulta SP-L in 500 g of water. After soaking or steeping the rinsed potato batons in the pectinase-solution for approximately 60 minutes, the solution was drained.

Next, the surface-treated potato batons were par-cooked. The surface-treated batons were arranged in one even layer inside a vacuum-sealed container with about 500 g of water and about 10 g of salt to taste. The surface-treated potato batons were steamed (par-Cooked) at 100° C. for about 15 minutes inside the container. After steaming, the water in the container was carefully drained and the par-cooked potato batons cooled.

Next, the par-cooked potato batons were further cooked through by blanching. The blanching also desiccated the surface layers of the par-cooked potato batons making them more suitable for storage and/or subsequent finish cooking. For example, the par-cooked potato batons were blanched in hot oil (about 170° C.) for about 3 minutes and then cooled. The oil-blanching process removed water from the surface layers of the par-cooked potato batons, for example, to help preserve or improve flavor and texture.

Finally, crispy pectinase-steeped French fries were obtained by deep frying the blanched potato batons in oil heated to approximately 190° C. for approximately 3 minutes and immediately transferred onto paper towels to drain any excess frying oil adhering to the fries. This process yielded about 350 g of suitably crisp and flavorful fries ready for serving.

EXAMPLE II Starch-Compressed Crispy Fries

Crispy French fries with compressed-starch outer surface layers were prepared. Russet potatoes (500 g) were cut into batons about 1.5 cm thick and thoroughly rinsed in water to wash away native surface starch. The surfaces of the rinsed potato batons were firmed up by a starch infusion process. In the starch infusion process, the rinsed potato batons were treated with a starch solution in a controlled environment. An approximately 50% water-based starch mixture was prepared by whisking 50 g of potato starch in 100 g of water. The rinsed potato batons and the starch mixture were combined in a container (e.g., a refrigerated container). A vacuum was drawn on the container to help compress/infuse starch into the surface layers. After treatment for about 30 minutes in a refrigerated vacuum-sealed container, the starch mixture was drained.

Next, the starch-infused potato batons were par-cooked. The starch-infused potato batons were arranged in one even layer and vacuum sealed in container with about 500 gm of water and salt (e.g., 10 g). The starch-infused potato batons in the container were steamed (par-cooked) at 100° C. for about 15 minutes. After steaming, the water in the container was carefully drained.

Next, the surface layers of the par-cooked potato batons were desiccated making them more suitable for storage and/or subsequent finish cooking. For example, the par-cooked potato batons were further dried in a vacuum sealer. For this purpose, the par-cooked potato batons (e.g., while hot) were placed on a wire rack in the vacuum sealer and vacuum pulled until the surfaces of the batons were suitably dry.

Then, the desiccated/dried potato batons were cooked through by blanching. The desiccated potato batons were blanched in hot oil (about 170° C.) for about 3 minutes and then cooled. The oil-blanching process may have further removed water from the par-cooked/desiccated potato batons making them suitable for storage or subsequent finish cooking and, for example, to preserve or improve flavor and texture.

Finally, crispy starch-compressed French fries were obtained by deep frying the blanched potato batons in oil heated to approximately 190° C. for approximately 3 minutes and immediately transferred onto paper towels to drain any excess frying oil adhering to the fries. This process yielded about 350 g of suitably crisp and flavorful fries ready for serving.

EXAMPLE III Ultrasonic Treated Crispy Fries

Crispy ultrasonic treated French fries were prepared.

Russet potatoes (500 g) were cut into batons about 1.5 cm thick and thoroughly rinsed in water to wash away native surface starch. Next, the rinsed potato batons were par-cooked. The batons were arranged in one even layer inside a vacuum-sealed container with about 500 g of water and about 10 g of salt. The rinsed potato batons in the container were steamed (par-cooked) at 100° C. for about 15 minutes, cooled and reserved.

Next, the par-cooked potato batons in the vacuum-sealed container were treated with ultrasound in a commercially available ultrasonic bath (Bransonic(R) Model 8510 Ultrasonic Bath sold Branson, 41 Eagle Rd., P.O. Box 1961, Danbury, Conn. 06813-1961). The nominal specifications of the Bransonic(R) Model 8510 ultrasonic bath used include: Tank Size (L-W-D): (19.5″-11.5″-6″); Overall Size (L-W-D): (24″-18″-14.5″); Tank Capacity: 5.5 gals; Weight: 26 lbs; Max. Input Power: 561 watts; Max Draw Power Req.: 881 watts; and Operating Frequency: 40 kHz.

The vacuum-sealed container with the par-cooked potato batons was placed in the ultrasound bath set to cavitate at full power for about 30 minutes. The ultrasound was expected to change the surface texture of the ultrasound treated potato batons, for example, by creating surface fissures and/or ridges on the so treated potato batons. The ultrasound treated potato batons were then further par cooked in the vacuum-sealed container by reheating to about 100° C. for about 5 minutes. After the reheating, water was carefully drained and the par-cooked ultrasonically treated potato batons cooled.

Next, the fissured surface layers of the par-cooked ultrasound-treated potato batons were desiccated making them more suitable for storage and/or subsequent finish cooking. For example, the par-cooked ultrasound-treated potato batons were further dried in a vacuum sealer. For this purpose, the par-cooked ultrasound-treated potato batons (e.g., while hot) were placed on a wire rack inside the vacuum sealer and vacuum pulled until the surface or surface layers of the potato batons were suitably dry.

Then, the desiccated potato batons were cooked through by blanching in hot oil heated to about 170° C. for about 3 minutes and then cooled. The oil-blanching process further removed water from the par-cooked/desiccated potato batons making them suitable for storage or subsequent finish cooking and, for example, to preserve or improve flavor and texture.

Finally, crispy ultrasonic treated French fries were obtained by deep frying the blanched potato batons in oil heated to about 190° C. for about 3 minutes and immediately transferred onto paper towels to drain any excess frying oil adhering to the fries. This process yielded about 350 g of suitably crisp and flavorful fries ready for serving.

EXAMPLE IV Ultrasonic Treated Starch-Compressed Crispy Fries

Crispy ultrasonic treated starch-compressed French fries were prepared. Russet potatoes (500 g) were cut into batons about 1.5 cm thick and thoroughly rinsed in water to wash away native surface starch. Next, the rinsed potato batons were par-cooked. The batons were arranged in one even layer inside a vacuum-sealed container with about 500 g of water and about 10 g of salt. The rinsed potato batons were steamed (par-cooked) at 100° C. for about 15 minutes inside the container.

The surfaces of the par-cooked potato batons were treated with a starch solution in a controlled environment to infuse starch into and firm up the surface layers after or while treating the surfaces with ultrasound: For this treatment, an approximately 50% water-based starch mixture was prepared by whisking 50 g of potato starch in 100 g of water. The par-cooked potato batons and the starch mixture were combined in a vacuum-sealable container. A vacuum was then drawn on the container to help compress/infuse starch into the surface layers. The container was placed in the Model 8150 ultrasound bath set to cavitate at full power for about 30 minutes. The ultrasound changes the surface texture of the ultrasound treated potato batons, for example, by creating surface fissures and/or ridges on the potato batons. Starch from the starch mixture was then infused/compressed into these surface fissures during the ultrasound treatment. After treatment with ultrasound for about 30 minutes in the vacuum-sealed container, the starch mixture was drained.

Next, the surface layers of the starch-compressed ultrasound-treated potato batons were desiccated making them more suitable for storage and/or subsequent finish cooking. For example, the starch-compressed ultrasound-treated potato batons were further dried in a vacuum sealer. For this purpose, the starch-compressed ultrasound-treated potato batons (e.g., while hot) were placed on a wire rack inside the vacuum sealer and vacuum pulled until the surfaces of the potato batons were suitably dry.

Then, the desiccated potato batons were further cooked through by blanching. The desiccated potato batons were blanched in hot oil at about 170° C. for about 3 minutes and then cooled. The oil-blanching process further removed water from the par-cooked/desiccated potato batons making them suitable for storage or subsequent finish cooking and, for example, to preserve or improve flavor and texture.

Finally, crispy starch-compressed ultrasound-treated French fries were obtained by deep frying the blanched potato batons in oil heated to about 190° C. for about 3 minutes and immediately transferred onto paper towels to drain any excess frying oil adhering to the fries. This process yielded about 350 g of suitably crisp and flavorful fries ready for serving.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. For example, in Examples II and IV excellent crispy textured fries may be obtained by placing the potato batons on one side in the ultrasonic bath for about 30-45 minutes and then flipping over the potato batons onto the other side for another 30-45 minutes of ultrasound treatment. It will be understood the various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims. listing, without prejudice, and with a full reservation of rights to pursue such cancelled claims in this application, a continuation application, and/or another application. 

1.-45. (canceled)
 46. A method of preparing vegetable pieces, comprising: sous vide cooking the vegetable pieces; and treating the sous vide cooked vegetable pieces with ultrasound.
 47. The method of claim 46, wherein the vegetable pieces are potato pieces.
 48. The method of claim 46, further comprising, removing at least a portion of native surface starch from the vegetable pieces prior to sous vide cooking the vegetable pieces.
 49. The method of claim 46, wherein treating the sous vide cooked vegetable pieces with ultrasound comprises placing the sous vide cooked vegetable pieces in an ultrasound bath.
 50. The method of claim 46, wherein treating the sous vide cooked vegetable pieces with ultrasound comprises placing the sous vide cooked vegetable pieces in a heated ultrasound bath.
 51. The method of claim 46, wherein sous vide cooking the vegetable pieces comprises steaming the vegetable pieces.
 52. The method of claim 46, wherein sous vide cooking the vegetable pieces comprises sealing the vegetable pieces in a container and immersing the container in a water bath.
 53. The method of claim 52, wherein immersing the container in a water bath comprises immersing the container in the water bath heated to a temperature at or below the boiling point of water (212° F.).
 54. The method of claim 46, further comprising, at least partially desiccating the ultrasound treated vegetable pieces.
 55. The method of claim 54, wherein at least partially desiccating the ultrasound treated vegetable pieces comprises pulling a vacuum on the vegetable pieces.
 56. The method of claim 54, wherein at least partially desiccating the ultrasound treated vegetable pieces comprises placing the vegetable pieces on a hot rack in a vacuum sealer.
 57. The method of claim 54, wherein at least partially desiccating the ultrasound treated vegetable pieces comprises blanching the vegetable pieces in oil.
 58. The method of claim 54, wherein at least partially desiccating the ultrasound treated vegetable pieces comprises blanching the vegetable pieces in oil at or about 170° C.
 59. The method of claim 46, further comprising, storing the ultrasound treated vegetable pieces.
 60. The method of claim 59, wherein storing the ultrasound treated vegetable pieces comprises packing the vegetable pieces in a container, removing air, and sealing.
 61. The method of claim 59, wherein storing the ultrasound treated vegetable pieces comprises freezing the vegetable pieces.
 62. The method of claim 46, further comprising, deep frying the ultrasound treated vegetable pieces in oil.
 63. The method of claim 62, further comprising, draining oil from the deep fried vegetable pieces.
 64. The method of claim 62, further comprising, serving the deep fried vegetable pieces as a food serving.
 65. The method of claim 46, wherein sous vide cooking the vegetable pieces and treating the sous vide cooked vegetable pieces with ultrasound comprise: rinsing the vegetable pieces; placing the vegetable pieces and water in a vacuum sealed bag; placing the vacuum sealed bag in a heated water bath for greater than about 1-5 minutes; further treating the vegetable pieces with ultrasound; placing the ultrasound treated vegetable pieces on a hot wire rack in a vacuum sealer to dry their surface; blanching the dried-surface vegetable pieces in oil at about 150-190° C. for about 1-5 minutes; and cooling and storing the blanched vegetable pieces.
 66. The method of claim 65, further comprising, deep frying the blanched vegetable pieces.
 67. The product made by the method of claim
 46. 68.-92. (canceled) 